The present invention relates to a fuel injection control device for an internal combustion engine. The present invention relates especially to a fuel injection control device for an internal combustion engine of a so-called fuel cylinder injection type which injects the fuel directly to the combustion chamber. More concretely, the present invention relates also to a fuel cylinder injection engine with a the supercharging machine.
The fuel cylinder injection engine with the supercharging machine is disclose in the Japanese Patent Application Laid-Open No. 2000-54894. In the fuel injection control device of this prior art, the fuel spray is divided within the range of the ignition time and the intake stroke when the acceleration is detected, and the fuel injection timing in the later term is set after the middle term of the compression stroke. The combustion gas is supplied to the exhaust side at shorter time after ignition, and high energy is given to the turbine of the turbocharger by making like this. Namely, the response of the turbocharger is improved.
However, it has been understood that the fuel spray is crushed by the pressure of the combustion chamber when the fuel spray is injected to the combustion chamber where pressure was improved by the supercharging machine, the fuel distribution in the center part of the fuel spray rises (in a word, the fuel spray concentrates on a specific part), and there is a tendency that the ignitability of the fuel deteriorates in the technology described in the above-mentioned Japanese Patent Application No. 2000-54894.
Moreover, the fuel is divided into the previous term and the later term of the compression stroke in the middle term of acceleration between the previous term of acceleration of the engine and the later term and injected in the above-mentioned prior art.
However, the total injection time of the fuel injection can do nothing but shorten because the time allowed for the fuel injection in the compression stroke shortens when the engine is comparatively in high loaded condition. Therefore, the problem that the injection in the previous term and the injection in the later term becomes close and the effect of divided injection is lost occurs.
Here, on the assumption of the slow acceleration in the stratification drive area where the previous term injection and the later term injection are continuously occurred (For instance, in the vicinity of 1 ms at the injection interval between the previous term injection and the later term injection), the driving current decreases due to shortage of the charging time of the voltage applied to the fuel injection valve, and injection amount on the later term side might decrease consequentially. The air/fuel ratio becomes lean when the injection amount decreases, and the accidental fire might occur.
Moreover, the power supply line voltage changes, because the electric load always changes by the drive of the auxiliary machine etc. Therefore, it is necessary to detect the change of the power supply line voltage, and to make the exhaust and the operability not influence.